Centralized data centers for computer, communications and other electronic equipment have been in use for a number of years, and more recently, with the increasing use of the Internet, large scale data centers that provide hosting services for Internet Service Providers (ISPs), Application Service Providers (ASPs) and Internet content providers are become increasingly popular. Typical centralized data centers contain numerous racks of equipment that require power, cooling and connections to communications facilities. It is common in data centers to use raised flooring, beneath which power cables and communication cables may be run between racks of equipment and to facility distribution panels. In addition, it is common to use the space beneath the raised flooring as an air plenum to provide cooling to the racks of equipment. In some facilities, in place of, or in addition to the use of raised flooring, overhead cable ladders are used to route cables throughout the facility. These cable ladders are typically fastened to support members in the ceiling of the facility.
It is often desirable to operate equipment within data centers seven days a week, 24 hours per day, with little or no disruption in service. To prevent any disruption in service, it is common practice in data centers to use uninterruptible power supplies (UPSs) to ensure that the equipment within the data centers receives continuous power throughout any black out or brown out periods. Typically, data centers are equipped with a relatively large UPS at the main power distribution panel for the facility. Often, the UPS is a 480 volt 3 phase unit that is selected to have sufficient capacity to meet the power requirements for all of the equipment within the facility.
Equipment within data facilities typically have 120 volt or 208 volt input power requirements, and a power distribution unit having a step down transformer is often used between the output of the UPS and power feeds for equipment racks to lower the 480 volt input voltage to 120 volts or 208 volts for the equipment racks. A circuit breaker panel is typically either installed in the PDU or mounted near the PDU.
There are several drawbacks with the traditional design of data centers. First, raised flooring is expensive and cannot be easily accommodated in some facilities, such as those that do not have high ceilings. Second, the routing of cables under raised floors often creates “rats' nests” and it often becomes difficult, if not impossible, to locate particular cables beneath a raised floor. Further, when it is desired to add new equipment to a data center having a raised floor, it is often difficult to pull cables past existing cables under the floor, and the build up of cables beneath a floor often prevents cooling air from flowing beneath the floor to electronic equipment racks. In addition, in many locations, building codes require that expensive metal clad cabling be used for power cables that are located beneath raised floors.
The use of cable ladders that run along the ceiling of a data center overcomes many of the drawbacks of raised floors discussed above, however, the use of cable ladders also has several drawbacks. Cable ladders are somewhat difficult to install, and like raised floors, cannot be readily accommodated in facilities that do not have high ceilings. Typically, when cable ladders are used, the location of the ladders is determined during the initial design of the data center. If it later becomes necessary to add new equipment to the data center or to move equipment, the location of the ladders may not be in close proximity to equipment racks, requiring long runs of cables to racks. Further, cable ladders and runs of cables from the ladders to equipment racks are typically fully in view and often cause a data center to appear to be overcrowded and/or cluttered.
Another drawback in the design of traditional data centers involves the difficulty in selecting the size of a UPS for the facility. As briefly discussed above, many newer data centers are used as web hosting facilities that essentially lease space and utilities to Internet content providers or Internet Service Providers. Often when these data centers are initially designed, the final power requirements for the facility are not known, and it is often not for some time, if ever, that a facility becomes fully occupied. If the UPS is selected for full capacity, and the facility is operated at substantially below full capacity for some time, then the overhead costs of the facility may become undesirably high due to the cost of the UPS. Further, there are power losses associated with a UPS. If a UPS is operated at substantially below full capacity, then these losses may become significant when compared with the total power consumption of the facility. If a UPS for a facility is selected for less than full capacity, then it may have to be replaced, at considerable cost, when the usage of the facility increases.
In some facilities, UPSs are distributed throughout the facility allowing smaller UPSs to be used, and providing greater flexibility. One problem with this approach is that installation of the UPS along with the wiring to racks often requires an electrician. In addition, a power distribution unit is often needed between each of the distributed UPSs and the loads that they power. These power distribution units are often bulky items that do not fit well within data centers, and/or may require placement near a wall on which a circuit breaker panel can be mounted.